Nothing in the poem says so outright, but the masks, the fear of a partner's breath, and the mention of being "grateful to stay alive" suggest a pandemic, with the ball standing in for life after lockdown. The music has returned, yet the party feels wrong. Faces are covered, smiles can't be seen, and even people once held close are now eyed warily, "as anyone."
The speaker sounds uneasy and a little bitter. The question "Why is it not more fun?" is plain and honest, as if the speaker expected relief and didn't find it. Fairy-tale and horror images pile up: a castle under siege, thorns that choke the sun, a dripping bat, spells that can't be undone. They make ordinary caution feel like an enchantment.
The form helps. The poem repeats whole lines, so the dancers keep whirling in the same circle. By the end, even the survivors, who should feel blessed, are checking the punchbowl for poison. The mood is eerie, wistful, and stuck.